The present invention relates to a capsule for preparing and delivering a beverage in a brewing device. The present invention more particularly aims at providing a capsule adapted to deliver brewed tea although other beverages can be successfully brewed in the capsule.
Different beverage capsules for brewing beverages in a suitable beverage machine are known. However, there is no existing capsule that can deliver a high quality tea beverage from a capsule containing leaf tea product and the like.
Quality of a tea beverage is highly dependent on the quality of the leaf tea ingredients, i.e., the tea origin used (soil, drying, blending, etc.) and their storage conditions. For instance, tea ingredients are usually sensitive to oxygen and light. Preferred tea ingredients are taken from loose leaves, chiselled or broken in small fragments. However, brewing conditions are also important to take full advantage of the quality of the ingredients used.
Another problem with tea beverages resides in that taste cross-contamination must be preferably avoided. Taste cross-contamination happens when two capsules are sequentially brewed in the machine and when a taste residue is left by the first capsule on permanent parts of the machine that can consequently affect the taste of the second capsule which is brewed just after the first capsule. For tea, this can be an issue with certain tea varieties that deliver a high aroma profile such as mint tea or other highly flavoured varieties. Also tea residue may constitute a soil for bacterial growth and may lead to hygiene issues which need to be tackled.
One commercially successful capsule system for extracting coffee beverage from capsules consists in placing an air- and water-impermeable capsule into an extraction device, injecting hot water into the capsule until the internal pressure in the capsule reaches the value at which a closing membrane is torn or pierced so that liquid extract can be released out of the capsule. A capsule adapted for such a process of extraction is described in EP 0 512 468. The process itself is described in EP 0 512 470. This method provides a high quality espresso-type coffee. The ground coffee is filled in the capsule fresh and can be stored many months without significant loss of aroma. The release of the coffee is slightly delayed due to a retarded opening of the membrane under pressure from the time water starts to be injected in the capsule. As a result, coffee can be fully extracted under optimal pressure and heat conditions. A stable and thick crema or foam is also produced due to high stress, pressure release and gas-entrapment conditions which are specific to this method.
However, such capsule and process are not optimal for carrying out the infusion or brewing of beverages such as tea or herbal tea. The result obtained is poor in term of taste; the beverage has a too high turbidity and may also comprise an undesired foam layer. Therefore, surprisingly a premium quality of tea beverage cannot be reached by such method.
Other capsule systems using pressure for brewing product can only deliver tea beverages that are too turbid, of poor product concentration and/or of taste that is not of sufficient quality for tea experts.
Capsules containing roast and ground coffee in which hot water flows under gravimetric force through the capsule are known. A capsule of this general type is described in British Patent No. 1397116. In this method, water is injected from the top of the cartridge and flows down through the ground coffee, through a filter and finally through a piercing hole or holes of the bottom side. More sophisticated systems are based on a similar approach using trunco-conical cartridges such as in US 2002/0148356 or using rectangular cartridges such as in US 2002/0148357.
EP 0 615 921 relates to a rigid cartridge for coffee, leaf tea or chocolate. The beverage package is used with water flowing in an upward direction. The sidewall of the package is formed from a water-impermeable material in order to encourage an even flow of water through the beverage package. One issue is that freshness of the ingredients cannot be maintained long enough unless an additional airtight package is utilized to over wrap the cartridge. Another problem with such solution lies in that beverage cannot be properly conducted to the recipient (cup, mug, glass, . . . ) after being released from the package.
EP 1 101 430 relates to a beverage filter cartridge system in which pressurized water (about 1.4 to 1.7 bar) is provided in downward direction through the upper side of the cartridge and beverage is collected from a lower side of the cartridge. This document also contemplates the solution in which the pressurized hot water is introduced through the bottom side and upwards into the beverage product. However, in this solution, the inlet traverses the filter and the product cake from bottom and water flows finally downward both through the fluid medium ingredients up to a bottom outlet. According to the patent application, the introduction of pressurized hot water squeezes the beverage powder into a cake and permeates the powder more efficiently.
EP 1 440 903 A1 relates to a cartridge used in a horizontal orientation. The cartridge has a bottom lid that is pierceable in use, by piercing members of a beverage preparation machine, in order to accommodate both inflow and outflow of an aqueous medium to form the beverage from interaction of the medium and the one or more beverage ingredients in the chamber. According to this document, the horizontal positioning of the cartridge during use allows for an optimised flow of the aqueous medium through the cartridge whereas, with vertically oriented cartridges, the water flows too quickly under the influence of gravity and may thus by-pass portions of the beverage ingredients. Therefore, this document claims that a horizontally oriented cartridge allows avoiding this problem, in particular, by arranging for an upward element of flow between the inlet and outlet positions.
However, one has surprisingly found that the darker brewed beverage portion tends to stay in the bottom of the cartridge because of its density that is higher than the rest of the beverage. Therefore, a beverage concentration gradient tends to form within the capsule with the denser beverage portion remaining in the bottom of the capsule; such portion being finally not delivered into the cup. As a result, the resulting tea beverage in the cup may be of insufficient quality despite the use of good quality ingredients. There is a need to overcome this problem.